Participants noted that there was some ambiguity about the randomisation method, and it was hard to pick out from the paper how many clusters of lots were ultimately randomised.

“E.g. P199 each cluster lot was viewed by PHS to determine if appropriate to send for greening authorisation? I didn’t fully understand this – seemed like a vetting process prior to randomisation, also unclear of randomisation method.” – @carotomes

“yes, it was a little unclear. I couldn’t work out how many clusters were randomised in the end” – @duncautumnstore

There was some discussion about whether the method used to group lots meant that the design was closer to a cluster RCT. It was noted that this would still be a strong design, but that that also more information should be provided when conducting a cluster RCT.

“I wondered that. Or whether it was closer in design to cluster-RCT” – @duncautumnstore

“absolutely – it was a cluster RCT rather than RCT. But no discussion of heterogeneity assessment” – @carotomes

Several of the difficulties of conducting an RCT on a built environment intervention were also discussed, as these may account for some of the compromises in study designed.

“not often you get the circumstances to do an RCT on the built environment, so maybe some compromises had to be made.” – @duncautumnstore

“[Pennsylvania is] big enough to fit a few more clusters into the trial… perhaps financial reasons, but we don’t know from the paper” – @duncautumnstore

3.Did the analysis use appropriate methods?

There was some discussion over the difference-in-differences method used, and whether any other statistical methods could have been used instead.

Participants found the difference-in-differences method intuitive, however, in the experience of the participants it rarely appeared in statistics text books. This made it harder to judge what the strengths and limitations are of using difference-in differences in this paper.

“I’d not come across difference-in-differences before. Not sure on its strengths and the right circumstances to use it.” – @duncautumnstore

4.Do you believe the results? The study reports non-significant reductions in crime and improvement in perceptions of disorder, but also a significant improvement in residents perceptions of safety, what could explain these findings?

The participants discussed that reductions in crime from green spaces seemed plausible, but given that there was some uncertainty over the methodology used in this study it was difficult to be more confident about some aspects of the results.

“I don’t know if I can be confident as I’m unclear about their methodology and analysis” – @carotomes

The authors also highlighted the preliminary nature of these results in the paper, and aspects of this were discussed by the participants.

“I get the feeling that the authors were a little tentitive from drawing too many certain conclusions too” – @duncautumnstore

The participants identified the potential for bias in the way that the questionnaire was used to measure the resident’s perceptions of safety.

“survey on perceptions of safety and violence primes interviewees of research purpose!” – @carotomes

5.What implications do the findings have for public health practice & policy?

The discussion of the implications referred back to the tentative nature of the findings. It was suggested that the focus of the paper could have been on the usefulness of the method rather than the results.

“feels like focus on paper should’ve been ‘is this method practical to test Q’ in prep of larger trial” – @carotomes

Research findings are essential for advocating for good public health, but one participant felt that the results from this paper weren’t striking enough to help advocate for green spaces.

“an important methods paper, but I don’t think the results are striking enough to be the one used to advocate for green spaces” – @duncautumnstore

The discussion will take place on twitter on Wednesday 31st July, at 8pm BST (GMT+1).

All are welcome to join the discussion at the Twitter Hashtag #PHTwitJC. If you have not joined a Twitter chat before, please see the ‘about’ tab above for some tips.

Introduction:

Green space can have a wide range of public health benefits, such as improving mental wellbeing and creating an area that are usable by the local community. Depending on the nature of the green space it can be used for play or exercise, leading to further benefits for the people and community who use it. From an aesthetic point of view, green spaces can be used to break up the monotony of urban environments and make it a lot more interesting and pretty!

This study is the first randomised controlled trial that examined whether converting disused areas into green spaces can reduce violence.

Paper Summary:

Method
The study used a Randomised Controlled Trial. 2,814 vacant lots were included in the study from a larger database of 54,132 vacant lots in Philadelphia in 2008. Lots in the same area were grouped together and then randomly assigned to receive ‘greening’ or to lie in their current state.

Intervention
Vacant lots were ‘greened’ by the Pennsylvania Horticulture Society (PHS) in May 2011. The greening process was done to a standard where PHS; removed debris, improved the soil, planted grass and trees and built a low wooden fence with opening around the lot. The site was maintained the site every two weeks. There is a before-and-after image in the paper.

ResultsReported crime – in the intervention area, 209 crimes were reported in the three and a half months before greening and 266 were reported during the same time period after. During the same time period at the control site, there was an increase in from 460 reported crimes before, to 521 crimes after. This meant that the unadjusted net difference-in-differences estimate was -4 at the greening site, which was a non-significant change (see table 2 for a break down of different types of crime).

Perceptions of disorder – A self-reported neighbourhood disorder scale was used to collect resident’s perceptions of disorder. An unadjusted difference-in-differences estimate was used again, and found that there was a reduction in perceptions of disorder at the intervention site compared with the control site. A regression-adjusted difference-in-differences estimate found that the differences were not significant.

The authors highlighted that a component of the perceptions of disorder scale that measures perceptions of safety found that this improved in the intervention site, and that this finding was highly significant when using both unadjusted and regression-adjusted difference-in-differences estimates.

Conclusion
The authors cocluded that the study ‘provides preliminary evidence that vacant lot greening may reduce violent crime and increase perceptions of safety’.

However, the authors also argued that larger trials would need to be conducted:

“Based on the findings of this smaller trial, these larger randomised trials will likely require hundreds of vacant lots in multiple study arms (greening intervention, trash pickup only and control) to have sufficient statistical power and detect meaningful effect sizes.”

It was suggested that this study provides a model for the larger trials.

Discussion Points:

1.Were the aims of this study clear? (consider whether it clearly defined the population, intervention, outcome and comparison)2.Was the methodology appropriate? (for instance: were appropriate methods used to identify vacant lots, randomise the lot, and select local participants?)3.Did the analysis use appropriate methods? (for instance: was the unadjusted difference-in-differences suitable for the comparisons)4.Do you believe the results? The study reports non-significant reductions in crime and improvement in perceptions of disorder, but also a significant improvement in residents perceptions of safety, what could explain these findings? (for instance: chance, bias, or confounding?)5.What implications do the findings have for public health practice & policy? (for instance: are the results applicable outside the US? What further research needs to be conducted?)

The next #PHtwitJC is on Wednesday the 31st July at 8.00pm (BST). All contributions are welcome – and this time @duncautumnstore will be a guest presenter.

The topic for the journal club is injury prevention. Injuries are often grouped into categories such as road injury, self-harm (including suicide), falls, interpersonal violence, drowning, or poisoning. Together they represent a major burden on health – traffic injuries alone are the eighth most common cause of death world-wide.

Whilst there are many interventions that limit the severity of injuries after or during the event that causes them, the papers selected for this journal club look at several different ways of preventing injuries from occurring, such as though advocacy, legislation, or the design of the built environment.

The full citations and URLs are listed below the poll. Please vote for your favourite that you’d like to discuss in the journal club. Voting will close late on Monday 22nd July.

Our live chat starts at 8.00 pm (BST) on Twitter and lasts for an hour. Join in and /or follow by using the hashtag #PHTwitJC. If you’ve never joined a Twitter chat before, see the ‘About’ tab above for some tips. Our ‘club’ is completely open – anyone can join in. If you miss the live hour, we will archive any comments / responses posted on the hashtag within the following 24 hours. Chats are summarised and archived here on the blog.

Introduction to the paper and questions for discussion

The issues

Ethical principles related to biomedicine are routinely referred to to guide clinical and research practice. While there are areas of debate and contention, ethics is well-established as an area of discussion in professions allied to medicine, and related research. However, until relatively recently, ethics in public health and specifically, health promotion, were addressed only implicitly. Frameworks from biomedical ethics, such as appeal to principles of autonomy, beneficence, non-maleficence and justice, are of limited benefit when considering the scope of health promotion actions:

“Under what circumstances, for example, would a health promotion perspective suggest that autonomy should be overridden in the interest of the greater good? What is health promotion’s response when considerations of social justice conflict with rights or the maximization of health gain?” (Sindall, 2002)

Evidence and ethics

In the article we are discussing, Carter et al propose that the evidence base and ethics base within health promotion practice /evaluation must be linked and underpinned by values. The role of evidence to inform health promotion is problematised.

While many interventions are applied with little underpinning evidence of effectiveness, growing awareness of the need for robust evidence has, they claim, led to a skewing of focus towards individual-level behaviour change interventions which are more amenable to evaluation using a trial design. Furthermore, they illustrate how there is little agreement within public health practice about the most desirable outcomes – for example, which is the more important- fitness, or body weight?

The authors identify two ethically-relevant concepts for consideration in body weight interventions.

Coercion may occur where choices and liberties are constrained (e.g. via structural interventions), or, the authors argue, where the public are manipulated or exposed to fear about risk, in order to initiate behaviour change.

Stigmatization occurs where individuals are linked to negative stereotypes; it can have serious, negative consequences for individuals’ sense of self. ( Weight stigma is a growing area of concern – see e.g. this recent conference on the issue).

They illustrate the discussion with the example of interventions regarding body weight. The specific case study used is an Australian social marketing campaign, Measure Up. The TV campaign adverts analysed can be viewed:

Developing a framework

Carter et al propose a framework that links their thinking on ethics, evidence and values in health promotion. A key aspect is the necessity for transparency and reflection about the ethical and evidential values underpinning a situation or intervention.

They then apply their framework to the ‘Measure Up’ campaign using the concepts of stigma and coercion:

Their results indicate that the ethical and evidential underpinnings of the campaign are questionable:

Conclusions

Overall, the authors present their framework as a set of ‘thinking tools’ to guide practice in health promotion, with a particular focus on transparency regarding ethical priorities in specific practice situations. They suggest that further ‘ethically relevant concepts’ need have their dimensions specified in the same way that stigmatization and coercion were addressed in this paper.

Questions for journal club:

1) Are the aims clear?
2) Who will be affected by these results? What is the scope?
3) Was the development of their framework justified and clearly explained?

4) Was the application of the framework to the case study (‘How do you measure up?’) transparent and reasonable?
5) What are the implications for policy/practice?

Further reading

If you are interested in further reading on public health ethics, try these books:

Next #PHTwitJC journal club live chat will take place on Monday 1st July at 2000-2100 hrs (British Summer Time). All are welcome.

The topic is ethics in public health. As befits the topic, the papers selected for the poll (all open access) are review-type /theoretical articles rather than primary research studies. Each of the papers does discuss ethics in relation to a specific public health topic.

Please vote for your favoured paper for discussion. Full citations and URLs are listed below the poll. Voting will close late on Wednesday 26th June.

HAVE, Marieke, Inez D de Beaufort, Johan P Mackenbach and Agnes van der Heide (2010). An overview of ethical frameworks in public health: can they be supportive in the evaluation of programs to prevent overweight? BMC Public Health 10:638. doi:10.1186/1471-2458-10-638 http://www.biomedcentral.com/1471-2458/10/638

We’ve had a great second year with 25 successful Journal Club sessions and over 10,000 hits to our website (https://phtwitjc.wordpress.com/) since we started in 2011. We are incredibly grateful for all the support, discussions and ideas generated by #PHTwitJC participants.

We’ve taken on board last years feedback; we’ve varied the time and day of #PHTwitJC discussions, chosen topics which you were most interested in, we’ve increased the time between poll, paper announcement and discussion, and we’re planning our first guest chair for later this year. Have these changes worked for you? What else can we do?

This quick evaluation survey should take 5-10 minutes to complete, and your feedback will help to shape #PHTwitJC moving into it’s third year of operation. So whether you’re a frequent contributor, occasional observer, or have never participated – we want to hear about how we can make #PHTwitJC work for you!